The invention relates generally to cutting inserts and, more particularly, relates to round cutting inserts having a seating surface that provides maximum contact between the round cutting insert and the insert-receiving pocket when mounted onto the body of a cutting tool.
The inserts used in tools such as, for example, milling cutters are mounted in complementarily-shaped pockets spaced around the periphery of the tool body. The inserts are typically secured within their respective pockets by clamping screws inserted through a hole provided in the center of the insert. During a cutting operation, such inserts often experience not only compressive and vibratory forces, but some amount of torque due to the angle between the cutting edges of the inserts and the workpiece. For cutting inserts of non-round shapes, such torque does not result in the rotation of the insert due to the interference-type fit between the angled sidewalls of such inserts and the complementarily-shaped walls of the pocket that receive them.
By contrast, round inserts can rotate within their respective pockets because no such mechanical interference naturally arises between the cylindrical or frustoconical sidewalls of round inserts and the corresponding circular walls of the pockets which receive them. The resulting rotation can loosen the clamping screw that secures the insert within its respective pocket. If the clamping screw should become sufficiently loosened, it can vibrate within the surrounding pocket severely enough to become chipped or cracked not only ruining the insert, but also jeopardizing the quality of the cut on the workpiece.
In addition, relatively large round inserts are exposed to higher cutting forces than smaller round inserts. As a result, large round cutting inserts have a tendency to move in a vertical direction (i.e. move up and down about the central axis of the insert) within the insert-receiving pocket during a cutting operation.